78 + 9 = 78 + 2 + 7 = 80 + 7 = 87
36 + 5 = 36 + 4 + 1 = 40 + 1 = 41
92 + 0 = 92
7 + 18 = 5 + 2 + 18 = 5 + 20 = 25
9 + 33 = 2 + 7 + 33 = 2 + 40 = 42
0 + 50 = 50
43 − 4 = 43 − 3 − 1 = 40 − 1 = 39
58 − 9 = 58 − 8 − 1 = 50 − 1 = 49
86 − 86 = 0
36 − 8 = 36 − 6 − 2 = 30 − 2 = 28
24 − 6 = 24 − 4 − 2 = 20 − 2 = 18
18 − 0 = 18